It is known that up to 10% of battlefield fatalities occur because soldiers bleed to death due to wounds inflicted on their proximal extremities, where it is often not possible to apply standard first aid methods, such as a tourniquet. For example, often, the only way to treat injuries to the femoral artery is to locate the artery and clamp it. In battlefield conditions, performing such work is not always possible, nor is it simple to do. Soldiers often operate in environments where it is cold, wet, and dark, making the medic's job that much more difficult. An injury to a major artery must be treated quickly to prevent life-threatening hemorrhage.
The average sized adult male's blood volume is approximately 6 liters. The loss of about 20% of this blood volume, without fluid replenishment to ensure blood pressure is maintained, is potentially fatal. With fluid replenishment it is possible for a person in good health to lose up to 50% of the blood volume without a transfusion and still survive, as long as the total circulation fluid volume remains around 6 liters. However, this type of intervention is often not possible in the field.
Many of these deaths could be prevented through the development of devices and techniques suitable for application in the field as temporary measures for immediate treatment. This is a problem that has, and continues to, receive much attention. Castaneda et al. (Castaneda, F., Swischuk, J. L., Smouse, H. B., Brady, T., “Gelatin Sponge Closure Device Versus Manual Compression After Peripheral Arterial Catheterization Procedures,” J. Vasc. Interv. Radiol., Vol. 14, No. 12, December 2003) evaluated the safety and efficacy of a porcine gelatin sponge intended to be used as an alternative to manual compression after a single interventional radiology practice. Their “QuickSeal” system delivers the extravascular sponge over a wire. Although this system appeared to provide benefit, it is unlikely that such an approach would be of use on the battlefield because it requires an operating theater environment and a small, clean wound.
Another study into the effectiveness of Arterial Puncture Closing Devices (APCD's) conducted by Koreny et al. (Koreny, M., Riedmuller, E., Nikfardjam, M., Siostrzonek, P., Mullner, M, “Arterial Puncture Closing Devices Compared With Standard Manual Compression After Cardiac Catheterization,” JAMA, Vol. 291, No. 3, January 2004) showed that many of the devices intended to accelerate the healing process after procedures such as coronary angiography and percutaneous vascular interventions are not very effective, and in some cases have negative effects. The study concluded that the APCD's analyzed showed only marginal evidence that they are effective and there is reason for concern that they may actually increase the risk of hematoma and pseudoaneurysm.
U.S. Patent Publication No. 2004/0013715 discloses an example of a hemostatic device containing a swellable polymer. However, the device described by the this patent publication does not appear to be ideally suited to preventing the clotting and gelling of blood from inhibiting absorption of blood by the polymer and preventing maximal swelling of the device.
While these and other conventional hemostatic materials and methods for controlling bleeding are potentially useful in certain situations and under certain conditions, a need exists for improved hemostatic devices and methods for their use.